Neurology -- Correspondence for Mink et al., 61 (6) 829-831

Correspondence published:

Progressive myoclonus in a child with a deep cerebellar mass: Gordon J Gilbert, MD, PA (16 December 2003)

Reply to Shetty and Gilbert: Jonathan W. Mink (16 December 2003)

Progressive myoclonus in a child with a deep cerebellar mass: Taranath Shetty (16 December 2003)

Progressive myoclonus in a child with a deep cerebellar mass 16 December 2003

Gordon J Gilbert, MD, PA,
Neurology and EEG
500 Pasadena Ave. South, St. Petersburgh, FL 33707
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Re: Progressive myoclonus in a child with a deep cerebellar mass

kathy_pieper{at}urmc.rochester.edu Gordon J Gilbert, MD, PA

In their article, Mink et al [1] relate their patient’s myoclonus to a ganglioglioma involving the right dentate and fastigial nuclei. The authors do not clearly integrate their report with the classic literature that has previously described the relationship of myoclonus to the dentate nucleus. In 1929, Morgan B. Hodskins and Paul I. Yakovlev [6] reviewed the literature concerning the pathologic findings in myoclonic epilepsy. They noted that in all twelve of the adequately studied cases, a lesion had been found in the dentate nucleus or in its efferent pathway, the brachium conjunctivum (superior cerebellar peduncle). They state, “From the standpoint of localization of the pathological lesion, it was found that in the cases of myoclonus without epilepsy, the lesion was confined to the dentate nucleus invariably”.
The case of Mink et al [1] is important since it relates a localized mass lesion to the occurrence of myoclonus, whereas the earlier literature has simply indicated a preponderance of dentate nuclear disease in such myoclonic disorders as dyssynergia cerebellaris myoclonica. [7]
References
6. Hodskins, MB and Yakovlev, PI. Anatomico-clinical observations on myoclonus in epileptics and on related symptom complexes. Amer. J. Psychiat. 1929;9:827-848.
7. Gilbert, GJ. Dyssynergia cerebellaris myoclonica. Handbook of Clinical Neurology, edited by J.M.B.V. de Jong, Elsevier Science Publishers 1991;43:593-606.

Reply to Shetty and Gilbert 16 December 2003

Jonathan W. Mink,
University of Rochester
Child Neurology, Box 631, 601 Elmwood Ave., Rochester, NY 14642
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Re: Reply to Shetty and Gilbert

Jonathan_Mink{at}urmc.rochester.edu Jonathan W. Mink

We appreciate Dr. Shetty’s interest in our article.[1] We are aware of the literature on hemifacial “seizures” or “spasms” associated with cerebellar ganglioglioma in which the jerking was demonstrated to be epileptic in origin. [2-4] We have reviewed the literature on “cerebellar seizures” and have considered the possibility that the abnormal movements in our case might have been “epileptic”. Certainly, a normal ictal scalp EEG does not rule out subcortical paroxysmal discharge. However, we disagree with Dr. Shetty that the mechanism of myoclonus in our patient is better regarded as epilepsy than myoclonus.
The phenomenology of the movements in our case was that of myoclonus. Myoclonus can certainly result from cortical discharge, as is seen in cortical myoclonus and myoclonic epilepsy. Myoclonus can also arise from the brainstem, spinal cord, and as we demonstrate, from the cerebellum. Presumably, myoclonus is due to paroxysmal neuronal discharge, regardless of the site of the myoclonus generator. Seizures are due to paroxysmal neuronal discharge. Thus, the argument seems a matter of taxonomy---“what is a seizure?” If a seizure is a paroxysmal neurologic event due to the repetitive discharge of a group or groups of neurons then myoclonus may indeed be seizures. While seizures are customarily viewed as cerebral cortical phenomena, it is reasonable to hypothesize that some types of paroxysmal movements may be due to subcortical paroxysmal neuronal discharge. One could make an argument for considering any paroxysmal movement disorder as “seizures”. [8]
Depth electrode recording was not done at the time of resection in our case. Thus, we don’t know if there was abnormal discharge in neurons surrounding the tumor. In a recent report of a case and review of nine other cases, Mesiwala et al. [2] make a compelling argument for the existence of “cerebellar seizures”. However, there are some clear differences between the 10 cases they reviewed and our case. 1) All of the cases in their review had facial movements that were tonic, clonic, or both. Our case had no facial movements. 2) The majority of their cases had eye deviation as part of the event. Our case had no eye deviation. 3) The duration of episodes in their cases ranged from 3 seconds to 30 minutes. Our case had movements that lasted less than one second. 4) Nine of the 10 cases had episodes that occurred both awake and asleep. No information was provided for the 10th. Our case only had movements occurring when awake. In light of these differences, we continue to think that the movements in our case are better described as myoclonus than as epileptic seizures.
We also thank Dr. Gilbert for calling attention to the classic paper by Hodskins and Yakovlev. [6] Unfortunately, space did not allow a comprehensive review of the literature and as may be the case too often, we favored more recent reports than the older ones.
References
8. Schlaggar BL, Mink JW. A 16-year-old with epidsodic hemidystonia. Sem Pediatr Neurol, 1999; 6:210-215.

Progressive myoclonus in a child with a deep cerebellar mass 16 December 2003

Taranath Shetty,
Brown University
80 Clarendon Avenue, Providence, RI 02906
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Re: Progressive myoclonus in a child with a deep cerebellar mass

tara_shetty{at}hotmail.com Taranath Shetty

Mink et al [1] report a 22-month old with myoclonus that resolved after surgical removal of a cerebellar ganglioglioma. The authors contend that this is a case of myoclonus due to abnormal cerebellar function rather than “cerebellar epilepsy”.
We managed an infant with increasing episodes of grimacing of face with rapid breathing and grunting lasting up to twenty seconds that started on the second day of life. EEG showed recurrent paroxysmal ictal discharges starting at the left frontal pole and spreading to involve the rest of the left hemisphere with clinical accompaniments. The seizures were refractory to Phenobarb and Dilantin at high therapeutic levels. Imaging showed a nonenhancing isodense mass in the fourth ventricle and lateral recess arising from the left cerebellar peduncles and lateral floor of the fourth ventricle with the fourth ventricle and quadrigeminal cistern displaced to the right without hydrocephalus. At surgery, the tumor was rising from the left superior and middle cerebellar peduncles. Pathologist classified the tumor as “gangliomatous hamartoma”. Surgical removal of the mass resulted in resolution of the seizures. The only deficits remaining at the current age of seven years are poor balance and inability to run.
Three single cases have been reported [2-4] of infants with cerebellar gangliogliomas and drug resistant seizures that resolved with surgical removal of the mass. All three had depth recordings of EEG showing focal discharges arising from the region of the cerebellar mass.
There are also previous reports of six infants with “hemifacial spasm”caused by cerebellar mass lesions.[3,5]Descriptive clinical data in these reports indicate that they all had eye deviation and dystonic limb movements in conjunction with the hemifacial spasm, suggesting that these were indeed epileptic phenomena even though scalp EEGs were normal. Four had surgical proof, three being gangliogiomas and one a low grade astrocytoma. The report by Harvey et al [3]cites two unpublished similar cases where one of them was a ganglioglioma.
The common features reported in the surgically proven cases include: onset in infancy, often the newborn period; the dysplastic nature of the cerebellar pathology (eight of the nine being gangliogliomas);lack of response to anticonvulsants; and total resolution of the episodic motor phenomena after surgical removal of the mass lesion.
These cases suggest that congenital dysplastic mass lesions in the cerebellum have a propensity to produce drug resistant epileptic manifestations of various types in the newborn period and infancy.
Some of these cases may have been wrongly classified in the published literature as hemifacial spasm or myoclonus of a nonepileptic pathophysiology.
References
1.Mink JW,Caruso PA, Pomeroy SL.Progressive myoclonus in a child with deep cerebellar mass. Neurology 2003;61:829-831
2.Mesiwala AH,Kuratami JD,Avellino AM,Roberts TS,Sotero MA,Ellenborg RG.Focal motor seizures with secondary generalization arising in the cerebellum-Case report and review of literature.J.Neurosurg 2002;97:190- 196.
3.Harvey As, Jayakar P,Duchowny M,Resnick T,Pratts A,Altman N,Renform JB.Hemifacial seizures and cerebellar ganglioglioma-An epilepsy syndrome of infants with seizures of cerebellar origin.Ann.Neurol 1996;40:91-98
4.Chase JH,Kim SK,Wang KC,Kim KJ,Hwang YS,Cho BK.Hemifacial seizures of cerebellar ganglioglioma origin-seizures controlled by tumour resection.Epilepsia 2001;42:1204-1207
5. Bills DC, Hanieh A.Hemifacial spasm in an infant due to fourth ventricular ganglioglioma-J.Neurosurg 1991;75:134-137